The present invention relates to a snap fastener and in particular to a socket and bulb snap fastener for Christmas light strings.
Decorative strings of multicolored lights are widely used around the world for decoration during many special occasions. They may be used as decoration on buildings or the like but most often are seen on Christmas trees. Although many new designs for filaments and sockets used in the strings as well as automatic assembling apparatus have been developed, an effective and secure construction of a snap fastener for securing the bulb in the socket has not yet been considered.
For example, as shown in FIG. 7, a conventional bulb and socket device in a light bulb string for a Christmas tree generally comprises a socket 90 formed with a hole 92 and a bulb 100 consisting of a lighting element 104 and an insert 102 including two leads 106 mounted on either side of the insert 102 and electrically connected to the lighting element 104. Such design provides for ease of assembly since the bulb is easily engaged with the socket 90 by inserting the insert 102 into the hole 92 of the socket 90. Nevertheless, such design is easily disconnected by sudden shock or vibration, which can occur when a string of lights hung outside swings in the wind or during transport. Moreover, in many Christmas light strings the sockets are electrically connected in series, so that the disconnection of even only one bulb breaks the electrical circuit rendering the entire string of light bulbs inoperable.